Hermetic Compressor

ABSTRACT

A hermetic compressor includes a hermetic container having an inner space, a cylinder accommodated in the hermetic container and arranged to compress refrigerant, an intake muffler accommodated in the hermetic container and having a silencer space having a longitudinal direction, a communication tube communicating with the cylinder, and a tail tube communicating with the inner space of the hermetic container. The communication tube and the tail tube have first and second opening ends opening in the silencer space, respectively. The first and second opening ends are located in a predetermined direction from a center of the silencer space along the longitudinal direction of the silencer space. A distance between the first opening end and the second opening end along the longitudinal direction is shorter than at least one of a distance between the first opening end and the center along the longitudinal direction and a distance between the second opening end and the center along the longitudinal direction. The hermetic compressor produces little noise and has a stable performance.

TECHNICAL FIELD

The present invention relates to a hermetic compressor of an inverter control type for use in refrigeration cycle apparatuses, such as an electric refrigerator.

BACKGROUND ART

Influences to global environment have been demanded to decrease, and accordingly, refrigeration cycle apparatuses, such as a refrigerator, are requested to generate less noise and to have high operational efficiency.

FIG. 5 is a cross sectional view of a conventional hermetic compressor 5001 disclosed in Japanese Patent Laid-Open Publication No. 2003-172265. A hermetic container 1 accommodates therein an electric power element 5 and a compressor element 6. The electric power element 5 includes a rotor 4 and a stator 93 with windings 3A. The compressor element 6 is driven by the electric power element 5. The hermetic container 1 contains lubrication oil 8 at a bottom thereof.

A crank shaft 10 includes a shaft portion 11 and an eccentric portion 12 having an axis deviated from that of the shaft portion 11. The rotor 4 is press-inserted into and tightened to the shaft portion 11. An oil pump 13 provided in the shaft portion 11 opens in the oil 8. A cylinder block 20 has a compression chamber 22 having a substantially cylindrical shape provided therein, and a shaft bearing 23 supporting the shaft portion 11. The cylinder block is located above the electric power element 5.

A piston 30 is inserted into the compression chamber 22 to reciprocate in the chamber 22, and is joined with a coupler 31 to the eccentric portion 12. A valve plate 32 seals the compression chamber 22. A movable valve 33 made of strip spring is mounted on the valve plate 21. An intake opening 34 communicates with the compression chamber 22. The movable valve 33 and the intake opening 34 provide an intake valve 35. A head 36 provides a high-pressure chamber, and is fixed to a side of the valve plate 32 opposite to the compression chamber 22. An intake tube 39 is fixed to the hermetic container 1, and communicates with a low-pressure side of the refrigeration cycle to introduce refrigerant gas of R134a into the hermetic container 1.

The hermetic container 1 is manufactured by press-forming a steel plate, and has a columnar resonant frequency of about 500 Hz when the refrigerant gas of R134a is used.

FIG. 6 is a front view of an intake muffler 40 of the hermetic compressor 5001. FIG. 7 is a cross sectional view of the intake muffler 40 at line 7-7 shown in FIG. 6. The intake muffler 40 is made of resin material having a silencer space 41 provided therein. The silencer space 41 includes chambers 40A and 40B separating from each other to left and right, and a communication space 40C for communicating between the chambers 40A and 40B. A communication passage 42 communicates between the movable valve 33 and the silencer space 41. The communication passage 42 is bent by about 50 degrees and extends into the silencer space 41, and has an opening end 42A opening in the silencer space 41. Communication passage 43 communicates between the silencer space 41 and inside of the hermetic container 1. The communication passage 43 has an opening end 43A opening in the silencer space 41. The chamber 40A functions as a resonant muffler having a resonant frequency of about 500 Hz.

An operation of the hermetic compressor 5001 will be explained below. The rotor 4 of the electric power element 5 drives the crank shaft 10 to rotate the eccentric portion 12. The rotation of the eccentric portion 12 is transmitted via the coupler 31 to the piston 30 to have the piston 30 reciprocate in the compression chamber 22. This reciprocating movement causes the refrigerant gas to flow from a refrigeration system into the hermetic container 1, and introduces the gas through the intake tube 39 into the inside of the hermetic container 1. The introduced refrigerant gas reaches the chamber 40B through the communication passage 43. Then the refrigerant gas passes through the communication passage 42 and the intake opening 34, and flows into the compression chamber 22 while the movable valve 33 opens. The refrigerant gas is compressed in the compression chamber 22 and returned back to the refrigeration system.

The movable valve 33 opens and closes when the refrigerant gas flows into the compression chamber 22. Upon opening and closing, the movable valve 33 may produce a pressure pulsation having various frequencies, and the pulsation is propagated in a direction reverse to the flowing direction of the refrigerant gas. A pressure pulsation out of the produced pulsation having a frequency of 500 Hz of a resonant mode reaches the inside of the hermetic container 1, and increases a noise at 500 Hz of the columnar resonant of the hermetic container 1. However, the chamber 40A provides the resonance muffler having the resonant frequency of 500 Hz, thereby reducing the pressure pulsation at 500 Hz in the chamber 40A.

In the conventional compressor 5001, the silencer space 41 of the intake muffler 40 necessarily provides a resonant muffler having a specific resonant frequency, hence preventing the intake muffler 40 from having a small size.

Upon reaching the silencer space 41, the refrigerant gas has its speed become small, accordingly separating the oil from the refrigerant gas. The opening end 42A of the communication passage 42 faces the opening end 43A, and this arrangement causes most of the refrigerant gas reaching the silencer space 41 to be transferred into the communication passage 42. Thus, the refrigerant gas containing a lot of oil is introduced into the compression chamber 22.

As explained above, the intake muffler 40 may fail to reduce the noise caused by the pulsation, and may introduce the refrigerant gas containing a lot of oil into the compression chamber 22, thus having the performance of the compressor 5001 decline.

DISCLOSURE OF THE INVENTION

A hermetic compressor includes a hermetic container having an inner space, a cylinder accommodated in the hermetic container and arranged to compress refrigerant, an intake muffler accommodated in the hermetic container and having a silencer space having a longitudinal direction, a communication tube communicating with the cylinder, and a tail tube communicating with the inner space of the hermetic container. The communication tube and the tail tube have first and second opening ends opening in the silencer space, respectively. The first and second opening ends are located in a predetermined direction from a center of the silencer space along the longitudinal direction of the silencer space. A distance between the first opening end and the second opening end along the longitudinal direction is shorter than at least one of a distance between the first opening end and the center along the longitudinal direction and a distance between the second opening end and the center along the longitudinal direction.

The hermetic compressor produces little noise and has a stable performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a hermetic compressor according to an exemplary embodiment of the present invention.

FIG. 2 is a cross sectional view of an intake muffler of the hermetic compressor according to the embodiment.

FIG. 3 is a cross sectional view of the intake muffler at line 3-3 shown in FIG. 2.

FIG. 4 shows an acoustic profile of the intake muffler according to the embodiment.

FIG. 5 is a cross sectional view of a conventional hermetic compressor.

FIG. 6 is a front view of an intake muffler of the conventional hermetic compressor.

FIG. 7 is a cross sectional view of the intake muffler at line 7-7 shown in FIG. 6.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a cross sectional view of a hermetic compressor 1001 according to an exemplary embodiment of the present invention. The hermetic compressor 1001 includes a compressor body 104 and a hermetic container 101 accommodating the compressor body 104 therein. The hermetic container 101 contains lubrication oil 102 at the bottom thereof. The compressor body 104 includes an electric power element 110 and a compressor element 120 driven by the electric power element 110. The hermetic container 101 is filled with hydrocarbon refrigerant, such as R600a, having a small global warming potential. A power source terminal 108 is mounted to the hermetic container 101 for connecting the electric power element 110 with a power source. The hermetic compressor 1001 has a height lower by about 20 mm than that of the conventional hermetic compressor 5001 shown in FIG. 5.

The electric power element 110 will be explained in detail. The electric power element 110 includes a DC brushless motor of a projection-pole concentration winding type including a stator 112 and a rotor 114. The electric power element 110 is connected via the power source terminal 108 with a conductor line to an inverter drive circuit.

The stator 112 includes a stator core having magnetic pole teeth and windings wound around the magnetic pole teeth. The stator core is made of electromagnetic steel material having a small iron loss. The windings are wound directly on insulator coatings covering entirely the magnetic pole teeth of the stator core. The rotor 114 includes a rotor core and a permanent magnet provided in the rotor core, and is fixed to a main shaft 122 of a crank shaft 121. The electric power element 110 is driven at plural frequencies ranging from 18 r/s to 81 r/s by the inverter drive circuit.

The compressor element 120 will be explained in detail. The compressor element 120 is located above the electric power element 110. The compressor element 120 includes a cylinder 130, a piston 128, the crank shaft 121, and an intake muffler 140.

The crank shaft 121 includes the main shaft 122 and an eccentric shaft 124. A lower end 122A of the main shaft 122 is immersed in the oil 102. The crank shaft 121 has a lubrication mechanism 125 extending from the lower end 122A of the main shaft 122 to an upper end 124A of the eccentric shaft 124. A block 126 includes the cylinder 130 and a bearing portion 127 supporting the main shaft 122 during rotation.

The piston 128 is accommodated in the cylinder 130 to reciprocate in the cylinder. The piston 128 provides a compression chamber 134 together with a valve plate mounted at one end of the cylinder 130, and compresses the refrigerant in the cylinder 130. The piston 128 is coupled to the eccentric shaft 124 with a coupler 136.

The intake muffler 140 is made of synthetic resin material, such as poly-butylene terephthalate or crystalline resin, containing fiber glass, and securely sandwiched between the valve plate 132 and a cylinder head 138.

FIG. 2 is a cross sectional view of the intake muffler 140 of the hermetic compressor 1001. FIG. 3 is a cross sectional view of the intake muffler 140 at line 3-3 shown in FIG. 2. The intake muffler 140 has a silencer space 142 provided therein, and includes a communication tube 150 and a tail tube 152. The communication tube 150 has an opening end 154 opening in the silencer space 142 and an opening end 156 communicating with the compression chamber 134 in the cylinder 130. The tail tube 152 has an opening end 158 opening in the silencer space 142 and an opening end 160 communicating with an inner space 141 in the hermetic container 101.

The opening end 154 of the communication tube 150 and the opening end 158 of the tail tube 152 are distanced in a predetermined direction 1142 out of a longitudinal direction 1140 of the silencer space 142 from a center 1141 of the silencer space 142 along the longitudinal direction 1140. The opening end 154 and the opening end 158 are arranged close to each other. More particularly, a distance L3 between the opening end 154 of the communication tube 150 and the opening end 158 of the tail tube 152 along the longitudinal direction 1140 is shorter than at least one of a distance L2 between the opening end 154 of the communication tube 150 and the center 1141 of the silencer space 142 along the longitudinal direction 1140 and a distance L1 between the opening end 158 of the tail tube 152 and the center 1141 along the longitudinal direction 1140. The communication tube 150 and the tail tube 152 extend along the longitudinal direction 1140 and passes through a plane 1145 which is perpendicular to the longitudinal direction 1140 and which includes the center 1141 of the silencer space 142 along the longitudinal direction 1140.

The opening end 154 of the communication tube 150 has an extending length larger than that of the opening end 158 of the tail tube 152 in the silencer space 142. In other words, the distance L2 is longer than the distance L1. The opening end 154 of the communication tube 150 is located above the opening end 158 of the tail tube 152.

A portion 212A of a wall 212 of the intake muffler 140 which defines the silencer space 142 provides the tail tube 152. The portion 212A, a portion of the tail tube 152, of the wall 212 of the intake muffler 140 is connected with an extension 214. The extension 214 inclines in a direction 1143 having the silencer space 142 flare.

An operation of the hermetic compressor 1001 will be explained below. When the inverter drive circuit energizes the electric power element 110, the stator 112 generates a magnetic field to rotate the rotor 114, accordingly rotating the crank shaft 121. As the main shaft 122 of the crank shaft 121 rotates, the eccentric shaft 124 rotates eccentrically. This eccentric rotation is concerted into a reciprocating movement via the coupler 136. This causes the piston 128 to reciprocate in the cylinder 130. The reciprocating movement of the piston 128 introduces the refrigerant gas in the hermetic container 101 into the compression chamber 134 to have the gas compressed. (a compressing process).

Due to the compressing of the refrigeration gas, the refrigerant gas in the hermetic container 101 is intermittently introduced into the compression chamber 134 via the intake muffler 140. The refrigerant gas is compressed, and is then sent via an exhaust tube to the refrigeration cycle outside the hermetic container 101. The intake muffler 140 reduces a pulsation noise produced by the intermittent introduction of the refrigerant gas. The intake muffler 140 is made of polybutylene terephthalate which has a heat propagation much smaller than that of metals, and reduces a temperature rise of the refrigerant gas having a low temperature returning from the refrigeration cycle, hence preventing a cooling performance of the refrigeration cycle from decline.

A silencing effect of the intake muffler 140 will be explained in detail. FIG. 4 shows an acoustic profile of the silencer space 142 in the intake muffler 140. In FIG. 4, the horizontal axis represents a frequency, and the vertical axis represents an acoustic pressure level released from an opening end 160 of the tail tube 152 of the intake muffler 140. The smaller the acoustic pressure level is, the greater the silencing effect is. FIG. 4 illustrates an acoustic profile 170 of the intake muffler 140 according to the embodiment as well as an acoustic profile 173 of an intake muffler of a comparative example. In the intake muffler of the comparative example, the opening end 158 of the tail tube 152 is located at the center 1141 along the longitudinal direction 1140 of the silencer space 142.

A main component of the pulsation noise produced in the hermetic container 101 is a resonant sound in the inner space 141 of the hermetic container 101. In the intake muffler 140 according to this embodiment, an anti-resonant frequency 171 of in the acoustic profile 170 is equal to the resonant frequency 162 in the inner space 141.

If the opening end 158 of the tail tube 152 is located farther from the opening end 154 of the communication tube 150 and is located closer to the center 1141 of the silencer space 142, the anti-resonant frequency 171 shifts towards higher frequencies, similarly to an anti-resonant frequency 174. An amount of the reduced noise declines as the anti-resonant frequency 171 approaches the resonant frequency 172, similarly to an amount of reduced noise at the anti-resonant frequency 174.

Thus, the opening end 158 of the tail tube 152 is preferably located farther from the center 1141 and closer to the opening end 154 of the communication tube 150, thereby increasing the amount of reduced noise at the anti-resonant frequency 171. A specific frequency of an outstanding pulsation noise produced in the hermetic compressor 1001 is identical to the anti-resonant frequency 171, thereby reducing the pulsation noise around the frequency.

Peaks P1 and P2 of the acoustic profile 170 at the resonant frequency 172 are larger than peaks P3 and P4 of the acoustic profile 173 at the resonant frequency 175 of the intake muffler of the comparative example. The resonant frequency 162 departs from the specific frequency of the outstanding pulsation noise, the pulsation noise is not amplified in the intake muffler 140, and is not released as a large noise from the hermetic compressor 1001.

Even if the silencer space 142 has a small volume due to the reducing of the size of hermetic compressor 1001 and resulting in reducing a silencing effect of the intake muffler 140, the muffler 140 has a large silencing effect at the specific frequency.

The specific frequency of the pulsation noise is determined to the resonant frequency 162 of the inner space 141 of the hermetic container 101, thereby reducing the pulsation noise from the hermetic compressor 1001.

The oil 102 stored at the bottom of the hermetic container 101 according to the compressing process is pumped up and supplied from the lower end 122A of the main shaft 122 to the upper end 124A of the eccentric shaft 124 by the lubrication mechanism 125 of the crank shaft 121. The oil is then sprayed and splashed to moving components of the hermetic container 101. While a portion of the oil becomes oil mist mixed with the refrigerant gas, most of the oil drops down and is stored at the bottom of the hermetic container 101.

The refrigerant gas 200 having the portion of the oil mixed therewith is introduced from the inner space 141 through the tail tube 152 to the silencer space 142, and then, is sucked into the opening end 154 of the communication tube 150. The opening end 154 of the communication tube 150 and the opening end 158 of the tail tube 152 face in the same direction 1142. Most of the refrigerant gas 200 discharged from the opening end 158 of the tail tube 152 is sucked into the silencer space 142 while contacting an outer wall 154A of the opening end 154 of the communication tube 150.

The oil mist mixed in the refrigerant gas 200 is attached to the outer wall 154A of the opening end 154 of the communication tube 150, thereby being allowing oil 102 to be separated from the refrigerant gas 200. The separated oil 102 drops down to the bottom of the silencer space 142 in the intake muffler 140. Then, the oil 102 passes through an oil outlet 178, and drained out to the inner space 141 of the hermetic container 101, then stored at the bottom of the hermetic container 101. Accordingly, the refrigerant gas containing a small amount of the oil mist is introduced into the cylinder 130, hence ensuring a stable performance of the hermetic compressor 1001.

The opening end 154 of the communication tube 150 extends longer than the opening end 158 of the tail tube 152. In other words, the opening end 154 of the communication tube 150 extends further than the opening end 158 of the tail tube 152 in the silencer space 142. That is, the distance L2 is longer than the distance L1. This arrangement increases the area of the outer wall 154A of the opening end 154 which the oil mist contacts, accordingly separating a large amount of the oil from the refrigerant gas 200 and providing the hermetic compressor 1001 with a high efficiency and a stable performance.

The opening end 154 of the communication tube 150 is located above the opening end 158 of the tail tube 152. This arrangement allows the outer wall 154A of the opening end 154 of the communication tube 150 to face towards a downward direction 1144. The oil 102 separated from the refrigerant gas and attached to the outer wall 154A of the communication tube 150 drops down to the bottom of the silencer space 142 of the hermetic container 101. The separated oil 102 is prevented from being sucked into the opening end 154 of the communication tube 150, accordingly allowing the refrigerant gas containing a small amount of oil mist to be introduced into the cylinder 130. Accordingly, the hermetic compressor 1001 has a high efficiency and a stable performance.

While the portion 212A of the wall 212 providing the tail tube 152 is also a portion of the wall 212 which defines the silencer space 142, the extension 214 of the wall 212 inclines in the direction 1143 to allow the silencer space 142 to flare. This structure allows the refrigerant gas 200 containing the oil mist to flow directly on and along the portion 212A of the wall 212, accordingly separating the oil 102 from the refrigerant gas 200 and causing the oil 102 to attached to the wall 212. The refrigerant gas 200 flowing from the opening end 158 of the tail tube 152 and enters into the silencer space 142.

The oil 102 attached to the wall 212 is then carried on extension 215 away from the refrigerant gas 200, and then drops down from extension 215 to the bottom of the silencer space 142. Accordingly, the refrigerant gas 200 taken into the opening end 154 of the communication tube 150 has a large purity containing a small amount of the oil, hence providing the hermetic compressor 1001 with a high efficiency and a stable performance.

The electric power element 110 of this embodiment includes the DC brushless motor having the windings concentrate-wound around the projection poles. The electric power element 110 may include an induction motor of a distributed winding type accompanied with the intake muffler 140 reducing the noise released from the compressor, hence providing the hermetic compressor with a stable performance and a small size.

The electric power element 110, employing a motor including rare earth magnets having large magnetic strength, can reduce the height, thus providing a hermetic compressor having the small height and producing a small noise.

The hermetic compressor 1001 of this embodiment can be driven operate throughout a wide range of revolutions by the inverter drive circuit. The splashed status of the oil 102 depends largely on the revolution. When the compressor 1001 is driven at high revolutions, a large amount of the oil 102 is splashed and carried easily into the intake muffler 140. The high revolution operation of the hermetic compressor 1001 of this embodiment causes the refrigerant gas to flow directly on and along the wall 212 of the tail tube 152, accordingly separating the refrigerant gas from the oil. The hermetic compressor 1001 prevents the oil 102 from entering into the compression chamber 134 throughout a wide range of revolutions, hence ensuring a high efficiency and a stable performance.

As set forth above, the hermetic compressor 1001 according to the embodiment allows the acoustic characteristics of the intake muffler 140 to be optimized, and separates the refrigerant gas reliably from the oil 102, hence having a stable performance and producing little noise.

It would be understood that the present invention is not limited to the foregoing embodiment.

INDUSTRIAL APPLICABILITY

A hermetic compressor according to the present invention produces little noise and has a stable performance, hence being useful not only for electric refrigerators but also for refrigerating apparatus, such as air conditioners and automatic vending machines.

REFERENCE NUMERALS

-   101 Hermetic Container -   101A Inner Space -   130 Cylinder -   140 Intake Muffler -   142 Silencer Space -   150 Communication Tube -   152 Tail Tube -   154 Opening End of Communication Tube 150 -   158 Opening End of Tail Tube 152 -   1001 Hermetic Compressor -   1140 Longitudinal Direction of Silencer Space 142 

1. A hermetic compressor comprising: a hermetic container having an inner space therein; a cylinder accommodated in the hermetic container and arranged to compress refrigerant therein; an intake muffler accommodated in the hermetic container, the intake muffler having a silencer space therein, the silencer space having a longitudinal direction; a communication tube having a first opening end opening in the silencer space, the communication tube communicating with the cylinder; and a tail tube having a second opening end opening in the silencer space, the tail tube communicating with the inner space of the hermetic container, wherein the first opening end and the second opening end are located in a predetermined direction from a center of the silencer space along the longitudinal direction of the silencer space, and a distance between the first opening end and the second opening end along the longitudinal direction is shorter than at least one of a distance between the first opening end and the center along the longitudinal direction and a distance between the second opening end and the center along the longitudinal direction.
 2. The hermetic compressor according to claim 1, wherein an anti-resonant frequency in the silencer space of the intake muffler is identical to a resonant frequency in the inner space of the hermetic container.
 3. The hermetic compressor according to claim 1, wherein the communication tube and the tail tube extend in the longitudinal direction.
 4. The hermetic compressor according to claim 1, wherein the distance between the first opening end and the center along the longitudinal direction is longer than the distance between the second opening end and the center along the longitudinal direction.
 5. The hermetic compressor according to claim 1, wherein the first opening end is located above the second opening end.
 6. The hermetic compressor according to claim 1, wherein the intake muffler includes a wall defining the silencer space, and the wall includes a portion providing the tail tube, and an extension extending in a direction allowing the silencer space to flare.
 7. The hermetic compressor according to claim 1, wherein oil is spattered in the inner space of the hermetic container. 